#include<bits/stdc++.h>
using namespace std;

#define pi 2.0*acos(0.0)
#define MOD 100000000
#define ll long long

void sumOfGroup(ll k) {
    vector<ll> store;
    ll i=1,change=1;
    while(i<=MOD) {
        ll count=0,sum=0;
        for(; count<change; i+=2) {
            sum+=i;
            count++;
        }
        //cout << sum << " ";
        store.push_back(sum);
        change++;
    }
    cout << store[k-1];
}

int main() {
    ll k;
    cin >> k;
    sumOfGroup(k);
}